276 NATURAL HISTORY. 



as well as corn : but that which breedeth the error 

 is, because after the chalking of the ground they 

 wear it out with many crops without rest, and then 

 indeed afterwards it will bear little grass, because 

 the ground is tired out. It were good to try the 

 laying of chalk upon arable grounds a little while 

 before ploughing ; and to plough it in as they do 

 the dung ; but then it must be friable first by rain 

 or lying. As for earth, it composeth itself; for I 

 knew a great garden that had a field, in a manner, 

 poured upon it, and it did bear fruit excellently the 

 first year of the planting : for the surface of the 

 earth is ever the fruitfullest. And earth so prepared 

 hath a double surface. But it is true, as I conceive, 

 that such earth as hath salt-petre bred in it, if you 

 can procure it without too much charge, doth excel. 

 The way to hasten the breeding of salt-petre, is to 

 forbid the sun, and the growth of vegetables. And 

 therefore if you make a large hovel, thatched, over 

 some quantity of ground ; nay, if you do but plank 

 the ground over, it will breed salt-petre. As for 

 pond earth, or river earth, it is a very good com 

 post; especially if the pond have been long un- 

 cleansed, and so the water be not too hungry : and 

 I judge it will be yet better if there be some mix 

 ture of chalk. 



597. The third help of ground is, by some other 

 substances that have a virtue to make ground fertile, 

 though they be not merely earth ; wherein ashes 

 excel ; insomuch as the countries about /Etna and 

 Vesuvius have a kind of amends made them, for the 



